checkpatch: ensure we do not collapse bracketed sections into constants

When determining if a return () sequence is a function style bracketing we
simplify the expression one bracket at a time replacing each with a
constant.  However this can trigger a false merge with expressions as
below:

	return (foo)0;

Prevent this false merging.
Reported-by: NHitoshi Mitake <mitake@dcl.info.waseda.ac.jp>
Signed-off-by: NAndy Whitcroft <apw@canonical.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

scripts/checkpatch.pl

@@ -2183,15 +2183,16 @@ sub process {
 			my $value = $2;
 
 			# Flatten any parentheses
-			$value =~ s/\)\(/\) \(/g;
+			$value =~ s/\(/ \(/g;
+			$value =~ s/\)/\) /g;
 			while ($value =~ s/\[[^\{\}]*\]/1/ ||
 			       $value !~ /(?:$Ident|-?$Constant)\s*
 					     $Compare\s*
 					     (?:$Ident|-?$Constant)/x &&
 			       $value =~ s/\([^\(\)]*\)/1/) {
 			}
-
-			if ($value =~ /^(?:$Ident|-?$Constant)$/) {
+#print "value<$value>\n";
+			if ($value =~ /^\s*(?:$Ident|-?$Constant)\s*$/) {
 				ERROR("return is not a function, parentheses are not required\n" . $herecurr);
 
 			} elsif ($spacing !~ /\s+/) {